Week 15: Energy Balance
Total energy baance: H1 + (ME)1 + C1 + G1 = H2 + (ME)2 + C2 + G2 + Q + W
Where
Me = mechanical energy
C = chemical energy
G = electrical energy
Q = heat
W = work
H = enthalpy
Heat Balance
The net energy flow into or out of the process is given by:
Q = ΣHout - ΣHin = ΔH
If there is no change of state, the enthalpy change (ΔH) is:
Mass x heat capacity x change in temperature (Q = mc∆𝑇 )
If there is a change of state (E.g. freezing or vaporisation), ΔH is:
Mass x Latent Heat (Q = m λ or Q = m 𝐿𝑓 or Q=m 𝐿𝑣)
Application of Energy Balance
Determine the energy requirement of a process
Evaluate energy efficiency
Trouble shooting